Tetrafluoroethylene is a very useful compound as a raw material of fluoropolymers such as fluororesins and fluororubbers, and fluorinated solvents. However, tetrafluoroethylene (hereinafter sometimes referred to as TFE) has very high polymerizability, and if it is stored in a gaseous state or a liquid state, it undergoes polymerization, and it may decompose by the heat of polymerization and explode. Therefore, in general, for the purpose of suppressing the polymerization reaction, various polymerization inhibitors are added when TFE is stored (the following Patent Document 1). However, if a polymerization inhibitor remains in TFE, a desired polymerization reaction will not proceed, whereby no fluoropolymer can be obtained. Accordingly, the polymerization inhibitor is removed immediately before TFE is used for the polymerization reaction or the like, and then it is subjected to polymerization.
As a method of removing the polymerization inhibitor from TFE, a method of distillation, absorption by sulfuric acid, or adsorption by silica gel, zeolite, allophane or the like has been known (the following Patent Documents 2, 3 and 4). Particularly, a method of adsorbing the polymerization inhibitor by silica gel is industrially useful since it can be carried out easily at a low cost. However, it has such problems that TFE is polymerized in the interior of the silica gel particles as porous bodies to form a polymer, which clogs the pores of the silica gel, whereby the performance of the silica gel to adsorb the polymerization inhibitor will be decreased, the used silica gel is hardened by the polymer, whereby removal of the silica gel from a packed column will be difficult, if TFE is polymerized, TFE will decompose by the heat of polymerization, etc.    Patent Document 1: U.S. Pat. No. 2,737,533    Patent Document 2: Japanese Patent No. 2,667,542    Patent Document 3: JP-A-11-246447    Patent Document 4: Japanese Patent No. 3,496,219